The year 2000 edition, which takes place around the world this weekend, finds the environmental movement bigger, better organized and more mainstream. But activists say they are still far from their goal of creating a sustainable human presence on the planet—especially by turning to non-polluting sources of energy in order to forestall global warming, the focus of this year’s event.

Global warming is "one of the most urgent environmental perils of our time," said Denis Hayes, who is reprising his role as national coordinator of the original Earth Day on April 22, 1970, by chairing this year’s event.

"The world’s leaders in Kyoto, Japan, in late 1997, acknowledged the scientific fact that the leading cause of global warming is carbon emissions from fossil fuel consumption, and that something must be done to address those rising emissions," said Hayes.

LITTLE PROGRESS ON TREATY

So far only 17 nations have ratified the global climate change treaty that grew out of the meeting. The pact calls for industrialized countries to sharply reduce their production of greenhouse gases resulting from use of fossil fuels such as coal and petroleum products.

Ratification by the U.S. Senate is seen as unlikely anytime soon, due to opposition from critics who say that developing countries like India and China should be held to similar standards.

While the political debate continues, more and more scientists are concluding that the current era of rising global temperatures is being caused at least in part by the burning of fossil fuels.

An early draft of a report now being developed by a blue-ribbon international scientific panel concludes that the rise in global temperatures over the past 150 years is "exceptional and unlikely to be solely natural in origin."

The Intergovernmental Panel on Climate Change—sponsored by the World Meteorological Organization and the United Nations—says that humans have "discernibly" influenced the climate and that surface temperatures are likely to rise between 2 and 9 degrees Fahrenheit (1-5 degrees Celsius) by the end of this century.

The consequences over the next few decades could be catastrophic, for example a relatively rapid rising sea level that could drown low-lying areas, including major coastal cities. The draft report estimates that the oceans could rise between 4 inches and 3 feet (10-90 centimeters).

To dramatize their message that the world should pay attention, Earth Day 2000 organizers on Saturday, April 22 are sponsoring hundreds of rallies, clean-energy demonstration projects and concerts in 181 countries. Major U.S. events will take place in Washington, Boston, Chicago and Los Angeles.

An all-day extravaganza dubbed EarthFair 2000 will held on the Mall near the U.S. Capitol. Movie mega-star Leonardo DiCaprio will introduce musicians James Taylor, Keb’ Mo’ and Third Eye Blind, and fellow actors Melanie Griffith and Chevy Chase.

TOUGH ACT TO FOLLOW

Earth Day 2000 has a tough act to follow. Organizers of the original 1970 version—originally conceived by then-U.S. Senator Gaylord Nelson (D) of Wisconsin, claim credit for massively increasing the level of environmental awareness among Americans, leading to creation of the U.S. Environmental Protection Agency and the passage of the Clean Air, Clean Water and Endangered Species acts.

The 1990 edition took a global perspective, with an estimated 200 million people in 141 countries rallying to put environmental issues on the world stage. In the United States this year’s Earth Day sponsors consist of 32 groups whose names are a who’s who of the environmental movement, from the Alliance to Save Energy to the World Wildlife Fund.

Organizers are making extensive use of a wonderful new device for coordinating activities around the world. And by the way, they point out, the Internet is non-polluting.

Eye in the Sky is a weekly series that brings you the story behind the headlines using satellite imagery, remote sensing, aerial photography, and maps. This feature is developed by National Geographic News with the sponsorship of the National Imagery and Mapping Agency (NIMA) and Earth-Info. Check out maps and imagery at http://www.earth-info.org.